J.R. Smith had a pretty great March. He was named Player of the Week recently and has just been an utterly terrific scorer. With his combination of shooting ability and athleticism, he can get plenty of good looks. He can also get plenty of terrible looks, which he'll take from time to time, but even then he has an uncanny talent to make some of those.
This is just a showing of insane athleticism and on a really cool dunk.